CN101528817B - Polyvinyl alcohol-based film for optical uses and polarizing membrane and polarizing plate - Google Patents

Abstract

It is intended to provide a polyvinyl alcohol-based film for optical uses which has an excellent stretchability and is usable in producing a polarizing membrane showing excellent polarization performance throughout the visible light wavelength range, in particular, at around 460 nm. Namely, a polyvinyl alcohol-based film for optical uses comprising a polyvinyl alcohol-based resin, wherein the polyvinyl alcohol-based resin consists of a polyvinyl alcohol-based resin (A) having a 1,2-glycol bond in a side chain alone and the content of the 1,2-glycol bond in the side chain amounts to 0.01 to 6% by mol.

Description

Polyvinyl alcohol base film for optics, polarizing film and polarizing plate

technical field

The present invention relates to a polyvinyl alcohol base film for optics. More specifically, the present invention relates to a polyvinyl alcohol-based film for optics, which is excellent in tensile properties, and is used to prepare a polarizing film excellent in polarizing properties in the entire visible light wavelength range, specifically around a wavelength of 460 nm . the

Background technique

Hitherto, polyvinyl alcohol-based films have been produced by dissolving polyvinyl alcohol-based resins in solvents such as water to prepare stock solutions, followed by film formation by solution casting (casting), and heating with metal Rolls or the like dry the film. The polyvinyl alcohol-based film thus obtained has been used in a large number of applications as a film excellent in transparency, and a polarizing film is exemplified as one of its useful applications. Such polarizing films have been used as basic constituent elements of liquid crystal displays, and in recent years their use has expanded to devices requiring high definition and high reliability. the

Under such circumstances, as brightness and definition of screens of liquid crystal televisions and the like increase, a polarizing film more excellent in optical performance than conventional polarizing films is required. the

For such demands, polarizing films obtained as a result of improving polyvinyl alcohol-based resins, such as polarizing films using a uniaxially stretched film containing a polyvinyl alcohol-based polymer as a base material, have been proposed in which polyethylene In alcohol-based polymers, the amount of 1,2-diol bonds directly bonded to the main chain is 1.8 mol% or more (see, for example, Patent Document 1); unit and 0.5 to 24 mol% of α-olefin units having 4 or less carbon atoms (see, for example, Patent Document 2) a polarizing film formed of a polyvinyl alcohol film of a vinyl alcohol-based polymer. Furthermore, as a means of improving the polarizing performance around the wavelength of 400 to 500 nm, it has been proposed to wash with at least 0.8% aqueous potassium iodide solution in the washing step which is the preparation step of the polarizing film (see, for example, Patent Document 3). the

Patent Document 1: JP-A-8-136728

Patent Document 2: JP-A-2003-248123

Patent Document 3: JP-A-2004-341503

Contents of the invention

technical problem

However, in the technologies disclosed in the above-mentioned Patent Documents 1 and 2, the polarizing film comprising the obtained polyvinyl alcohol base film has insufficient polarizing performance near 460 nm in the visible light wavelength range, so there is a problem that the gray scale of the liquid crystal display is not improved. Display performance and contrast issues, so hope for further improvement. Furthermore, in the technology disclosed in Patent Document 3, although the polarization performance in the vicinity of 400 to 500 nm can be improved, the technology has a problem that foreign particles on the film are washed by washing the film with water mixed with inorganic substances. (optical defects) increase. the

Against such a background, an object of the present invention is to provide a polyvinyl alcohol-based film for optics, which is excellent in stretchability, and which can be used to produce polarizing films in the entire visible light wavelength range, specifically, even under conventional polarizing film production conditions. Polarizing film with excellent polarizing performance near the wavelength of 460nm. the

Technical solutions

As a result of intensive research to solve the above-mentioned problems, the present inventors have found that by using a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on the side chain as the polyvinyl alcohol-based resin, it is preferable to use Tensile properties are obtained by using in combination a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on a side chain and a polyvinyl alcohol-based resin (B) other than the polyvinyl alcohol-based resin (A) It is an excellent polyvinyl alcohol-based film that is used to prepare a polarizing film with excellent polarizing properties around a wavelength of 460nm. Thus, they completed the present invention. the

That is, the gist of the present invention relates to a polyvinyl alcohol-based film for optics comprising a polyvinyl alcohol-based resin consisting only of the following polyvinyl alcohol-based resin (A) (A) containing 1,2-diol bond on the side chain and the amount of 1,2-diol bond on the side chain is 0.01 to 6 mol%; or polyvinyl alcohol for optics comprising polyvinyl alcohol-based resin A base film, wherein the polyvinyl alcohol-based resin comprises a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on a side chain and a polyvinyl alcohol-based resin other than the polyvinyl alcohol-based resin (A) (B), and satisfy the following formula (1):

0.01≤A×G/(A+B)≤6(1)

Among them, A represents the content ratio (weight ratio) of the polyvinyl alcohol-based resin (A) based on the total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), and B represents the polyvinyl alcohol-based resin (A) based on the total amount of the polyvinyl alcohol-based resin (B). The content ratio (weight ratio) of the vinyl alcohol-based resin (B), G represents the amount (mol%) of 1,2-diol bonds on the side chain. the

Furthermore, in the present invention, 1,2- The content of the diol-bonded polyvinyl alcohol-based resin (A) is preferably 50% by weight or less. the

In the present invention, it is preferable that the film further contains a plasticizer (C) and/or a surfactant (D). the

Furthermore, in the present invention, it is preferable that the width of the film is 2 m or more, and the thickness of the film is 30 to 70 μm. the

In addition, the present invention also provides a polarizing film including the above polyvinyl alcohol film for optics, and further provides a polarizing plate including the polarizing film and a protective film provided on at least one surface of the polarizing film. the

Invention effect

The polyvinyl alcohol-based film for optics of the present invention is a polyvinyl alcohol-based film excellent in stretchability and has the effect of obtaining a polarizing film excellent in polarizing properties in the entire visible light wavelength range, specifically around a wavelength of 460 nm. The film is used as a raw film for polarized sunglasses and a liquid crystal display device such as a polarizing film of a liquid crystal television, as a raw film for a 1/2 wavelength plate and a 1/4 wavelength plate, and as a It is very useful as a raw material film for a retardation film of a liquid crystal display device. the

Detailed ways

The polyvinyl alcohol base film for optics of the present invention is: wherein the polyvinyl alcohol base film used is composed only of a polyvinyl alcohol base resin (A) containing 1,2-diol bonds on the side chain and on the side chain The amount of 1,2-diol bond is 0.01～6 mol% of film; A polyvinyl alcohol-based resin (B) other than the resin (A) and a film satisfying the above formula (1). the

As the polyvinyl alcohol-based resin (A) used in the present invention, there can be mentioned a polyvinyl alcohol-based resin (A) containing a 1,2-diol bond in the side chain, that is, generally a polyvinyl alcohol-based resin (A) comprising the formula (1) Polyvinyl alcohol-based resins represented by 1,2-diol structural units: 

Chemical formula 1:

In the formula, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group.

Such a polyvinyl alcohol-based resin (A) can be produced, for example, by (A) saponifying a copolymer of vinyl ester-based monomers with 3,4-bisacetoxy-1-butene. the

As such vinyl ester-based monomers, there may be mentioned vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate ester, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versatate, etc. Specifically, vinyl acetate is preferably used. the

The 3,4-bisacetoxy-1-butene to be copolymerized with this vinyl ester monomer is represented by the following chemical formula (2):

Chemical formula 2:

Wherein, R represents an alkyl group, preferably a methyl group. the

In this regard, the compound represented by the above-mentioned formula (2) is available as a product of Eastman Chemical Company and Across Company, or an intermediate in the production of butanediol after purification can be used. the

In addition, in the present invention, the above-mentioned copolymer is preferably used, but optionally, other monomers may be copolymerized in a small amount, such as 5 mol% or less, in a range that does not limit the purpose of the present invention, in addition to the above-mentioned copolymerizable components . For example, mention may be made of olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene and α-octadecene; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic acid, Anhydrides and itaconic acid or their salts or their mono- or di-alkyl esters; nitriles such as acrylonitrile and methacrylonitrile; amides such as diacetone acrylamide, acrylamide and methacrylamide; olefinic sulfonates Acids such as ethylene sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid or their salts; glycerol monoallyl ether, alkyl vinyl ether, dimethylallyl ketene, N-ethylene ylpyrrolidone, vinyl chloride, vinylidene chloride, polyoxyalkylene(methyl)allyl ether such as polyoxyethylene(meth)allyl ether and polyoxypropylene(meth)allyl ether; polyoxyalkylene(meth)allyl ether; (Meth)acrylates such as polyoxyethylene (meth)acrylate and polyoxypropylene (meth)acrylate; polyoxyalkylene (meth)acrylamides such as polyoxyethylene (meth)acrylamide and polyoxypropylene (Meth)acrylamide; Polyoxyethylene (1-(meth)acrylamide-1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, Polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine, ethylene carbonate, allyl acetate, etc. the

Furthermore, mention may also be made of monomers containing cationic groups such as N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidopropyltrimethylammonium chloride Ammonium Ammonium Chloride, 2-Acryloyloxyethyltrimethylammonium Chloride, 2-Methacryloyloxyethyltrimethylammonium Chloride, 2-Hydroxy-3-methacryloyloxypropyltrimethylammonium Chloride Trimethyl ammonium chloride, allyl trimethyl ammonium chloride, methyl allyl trimethyl ammonium chloride, 3-butene trimethyl ammonium chloride, dimethyl diallyl ammonium chloride, di Ethyldiallylammonium; acetoacetyl-containing monomers, etc. the

In the copolymerization reaction of the above-mentioned vinyl ester-based monomers with 3,4-bisacetoxy-1-butene (and further other monomers), a method similar to known ones for vinyl ester-based monomers can be used. Methods for aggregation conditions and aggregation methods. the

As the polymerization method, a known method such as bulk polymerization, solution polymerization, suspension polymerization, dispersion polymerization or emulsion polymerization can be used, but solution polymerization is usually used. the

The method for adding monomer components in the polymerization is not particularly limited, and any method such as adding all at once, adding separately, or adding continuously may be used, but considering adding 3,4-bisacetoxy-1-butene in the polymerization For physical properties such as uniform distribution in the molecular chain of the vinyl ester-based polymer and lowering of the melting point of polyvinyl alcohol, dropping polymerization (dropping polymerization) is preferred, and a polymerization method based on the HANNA method is particularly preferred. the

As the solvent used for this copolymerization, there can be mentioned lower alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone and methyl ethyl ketone and the like, and methanol is suitably used industrially. the

The amount of the solvent to be used can be appropriately selected in consideration of the chain transfer constant of the solvent according to the degree of polymerization of the target copolymer. For example, when the solvent is methanol, its amount is selected from the following range: S (solvent)/M (monomer) = 0.01-10 (weight ratio), preferably about 0.05-about 3 (weight ratio). the

At the time of copolymerization, a polymerization catalyst is used. As such a polymerization catalyst, there may be mentioned, for example, known radical polymerization catalysts such as azobisisobutyronitrile, acetyl peroxide, benzoyl peroxide, and lauryl peroxide; radical polymerization active at low temperature Catalysts such as azobis(dimethylvaleronitrile) and azobis(methoxydimethylvaleronitrile) and the like. The amount of the polymerization catalyst to be used varies with the kind of the catalyst, and is not absolutely determined, but is optionally selected according to the polymerization rate. For example, in the case of using azoisobutyronitrile or acetyl peroxide, the amount thereof is preferably 0.01 to 0.2 mol%, specifically 0.02 to 0.15 mol%, based on the vinyl ester-based monomer. the

In addition, the reaction temperature of the copolymerization reaction is preferably about 40° C. to boiling point, depending on the solvent and pressure used. the

In the present invention, the copolymerization ratio of 3,4-bisacetoxy-1-butene is determined according to the introduced amount of 1,2-diol bond described below. the

The obtained copolymer is then subjected to saponification, and the saponification reaction is substantially the same as the saponification conditions used for known polyvinyl alcohol-based resins. That is, the copolymer obtained above is generally dissolved or dispersed in alcohol or aqueous alcohol, and saponified using a basic catalyst or an acidic catalyst. As the alcohol, methanol, ethanol, propanol, tert-butanol and the like can be mentioned, and methanol is particularly preferably used. The concentration of the copolymer in alcohol is appropriately selected according to the viscosity of the system, but is usually selected from the range of 10 to 60% by weight. As the catalyst used for saponification, there may be mentioned basic catalysts including alkali metal hydroxides or alkoxides such as sodium hydroxide, potassium hydroxide, sodium methoxide, sodium ethoxide, potassium methoxide, and lithium methoxide; and acid catalysts such as sulfuric acid, Hydrochloric acid, nitric acid, methanesulfonic acid, zeolites and cation exchange resins. the

The amount of such a saponification catalyst to be used is appropriately selected depending on the saponification method, the target degree of saponification, etc., however, in the case of using a basic catalyst, generally, per 1 mole of vinyl ester-based monomer and 3,4-bis The total amount of acetoxy-1-butene is suitably 0.1 to 30 millimoles, preferably 2 to 17 millimoles. the

In addition, the reaction temperature of the saponification reaction is not particularly limited, but is preferably 10 to 60°C, more preferably 20 to 50°C. the

The above-mentioned polyvinyl alcohol-based resin (A) is prepared by simultaneously converting the ester moiety of the vinyl ester-based monomer and the acetoxy moiety of 3,4-bisacetoxy-1-butene into hydroxyl groups in the above-mentioned saponification reaction. the

Thus, a polyvinyl alcohol-based resin (A) having a 1,2-diol bond in the side chain is obtained. In the present invention, it is preferable that the degree of saponification of the polyvinyl alcohol-based resin (A) is generally 90 mol% or more, specifically 95 mol% or more, further 98 mol% or more. When the degree of saponification is too small, water resistance in preparing a polarizing film tends to be insufficient. the

In this regard, the degree of saponification in the present invention is represented by the conversion ratio of the total amount of the ester moiety of the vinyl ester-based monomer and the acetoxy moiety of 3,4-bisacetoxy-1-butene into hydroxyl groups (in saponification During the reaction, the acetoxy moiety of 3,4-bisacetoxy-1-butene is almost completely saponified). the

Furthermore, it is preferable that, in the case of using at least one selected only from polyvinyl alcohol-based resins (A), the viscosity of the above-mentioned polyvinyl alcohol-based resin (A) is generally 8 to 400 mPa·s, specifically 40 to 300 mPa·s, further 50 to 270 mPa·s. When the viscosity of this 4% by weight aqueous solution is too small, stretchability in preparing a polarizing film tends to be insufficient, and when the viscosity is too large, the surface smoothness and transparency of the film tend to decrease. Furthermore, it is preferable that in the case of using the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) in combination, the viscosity of the polyvinyl alcohol-based resin (A) is usually 8 to 400 mPa·s, specifically 12 to 300 mPa·s, further 16 to 270 mPa·s. When the viscosity of the 4% by weight aqueous solution is too small, stretchability in preparing a polarizing film tends to be insufficient, and when the viscosity is too large, the surface smoothness and transparency of the film tend to decrease. the

Also, in the case of using at least one kind selected only from polyvinyl alcohol-based resins (A), the amount of 1,2-diol bonds introduced into side chains of polyvinyl alcohol-based resins (A) is 0.01 ~6 mol%, preferably 0.05-4 mol%, particularly preferably 0.1-3 mol%. When the amount is less than the lower limit, the advantages of the present invention cannot be obtained, and when the amount exceeds the upper limit, water resistance in preparing a polarizing film becomes insufficient. Also, in the case of using the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) in combination, the 1,2-diol bond introduced into the side chain of the polyvinyl alcohol-based resin (A) The amount is 0.01 to 20 mol%, preferably 0.05 to 15 mol%, particularly preferably 0.1 to 12 mol%. When the amount is too small, it is difficult to obtain the advantages of the present invention, and when the amount is too large, production of polyvinyl alcohol-based resin tends to be difficult. the

In addition, as a method for preparing the polyvinyl alcohol-based resin (A) used in the present invention, (A) saponification of the copolymerization of the above-mentioned vinyl ester-based monomer with 3,4-bisacetoxy-1-butene is described in detail the above-mentioned method of the object. However, the method is not limited thereto, and there may be mentioned, for example, (B) a method of saponifying and decarboxylating a copolymer of a vinyl ester-based monomer and ethylene carbonate represented by the general formula (3), (c) A method of saponifying a copolymer of a vinyl ester-based monomer and a 2,2-dialkyl-4-vinyl-1,3-dioxolane represented by the general formula (4) and performing solvolysis of a ketal structure, (d) A method of saponifying a copolymer of a vinyl ester-based monomer and glycerol allyl ether, etc., without limitation. In this regard, ethylene carbonate is commercially available (eg, a product of Eastman Chemical Company). the

Chemical formula 3:

Wherein, R ¹ , R ² and R ³ each independently represent a hydrogen atom or an alkyl group.

Chemical formula 4:

Wherein, R ¹ , R ² , R ³ , R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group.

In the present invention, as described above, in the case where the polyvinyl alcohol-based resin consists of only the polyvinyl alcohol-based resin (A), excellent suitability as an optical film is exhibited. However, in the present invention, it is more preferable to use the above-mentioned polyvinyl alcohol-based resin (A) in combination with another of the above-mentioned polyvinyl alcohol-based resins other than the polyvinyl alcohol-based resin (A) in view of further improvement in tensile properties and dyeing properties. (B). the

In the present invention, as the polyvinyl alcohol-based resin (A), polyvinyl alcohol-based resins different in the amount of 1,2-diol bond, degree of saponification, viscosity of 4% by weight aqueous solution, and the like can be used in combination. the

The polyvinyl alcohol-based resin (B) used in the present invention is not particularly limited, but usually the degree of saponification is preferably 90 mol% or more, particularly preferably 95 mol% or more, further preferably 98 mol% or more. When the degree of saponification is too small, water resistance in the production of a polarizing film tends to be insufficient. the

In addition, as the viscosity of the 4% by weight aqueous solution, the polyvinyl alcohol-based resin (B) preferably has a viscosity of usually 8 to 500 mPa·s, specifically 20 to 400 mPa·s, further 40 to 400 mPa·s. When the viscosity of the 4% by weight aqueous solution is too small, the stretchability in preparing a polarizing film tends to be insufficient, and when the viscosity is too large, the surface smoothness and transparency of the film tend to decrease. the

The polyvinyl alcohol-based resin (B) is not particularly limited as long as it is a polyvinyl alcohol-based resin other than the polyvinyl alcohol-based resin (A), but usually an unmodified polyvinyl alcohol-based resin is preferred. Likewise, it may be a polyvinyl alcohol-based resin containing a small amount of components copolymerizable with vinyl acetate, such as unsaturated carboxylic acids (including salts, esters, amides or Nitriles), olefins with 2 to 30 carbon atoms (ethylene, propylene, n-butene, isobutene, etc.), vinyl ethers, unsaturated sulfonates, and the like. the

In addition, as the polyvinyl alcohol-based resin (B), polyvinyl alcohol-based resins different in the amount of saponification degree, viscosity of 4% by weight aqueous solution, and the like can be used in combination. the

In the present invention, when polyvinyl alcohol-based resin (A) and polyvinyl alcohol-based resin (B) are included, the polyvinyl alcohol-based resin preferably satisfies the following formula (1), specifically the following formula (2), And it is further preferable to satisfy the following formula (3). the

0.01≤A×G/(A+B)≤6(1)

0.05≤A×G/(A+B)≤4(2)

0.1≤A×G/(A+B)≤2(3)

In the formula, A represents the content ratio (weight ratio) of the polyvinyl alcohol-based resin (A) based on the total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), and B represents the content ratio (weight ratio) based on the above-mentioned total amount. The content ratio (weight ratio) of the polyvinyl alcohol-based resin (B), G represents the amount (mol%) of 1,2-diol bonds on the side chain. the

In the above formula (1), when the value is less than the lower limit, it is difficult to obtain the advantages of the present invention, and when the value exceeds the upper limit, water resistance in preparing a polarizing film tends to be insufficient. the

In the present invention, the polyvinyl alcohol-based resin (A) containing a 1,2-diol bond on the side chain is based on the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based The total amount of polyvinyl alcohol-based resins (B) other than the resin (A) is preferably 50% by weight or less, and the content is particularly preferably 5 to 50% by weight, more preferably 10 to 40% by weight. When the content of the polyvinyl alcohol-based resin (A) is too small, excellent polarizing properties around a wavelength of 460 nm tend to be difficult to obtain, while when the content is too large, tensile properties tend to decrease in preparing a polarizing film. the

In addition, when the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) are contained, in consideration of the transparency of the film, the difference between the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) The difference in degree of saponification is preferably 6 mol% or less, particularly preferably 3 mol% or less. When the difference in the degree of saponification is too large, the light transmittance of the film tends to decrease. the

Furthermore, in the present invention, it is preferable to contain a plasticizer (C) and a surfactant (D) in addition to the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B). the

The plasticizer (C) used in the present invention contributes to the tensile properties in the preparation of the polarizing film, for example, polyhydric alcohols such as ethylene glycol, glycerol, propylene glycol, diethylene glycol, diglycerol can be mentioned Alcohol, triethylene glycol, tetraethylene glycol, trimethylolpropane, and polyethylene glycol with a degree of polymerization of 300 or less. These polyols may be used alone or in combination of two or more thereof. Among them, particularly preferably, glycerol alone or combinations of glycerol and diglycerol, glycerol and trimethylolpropane, and the like can be mentioned. the

The content of the plasticizer (C) is preferably 1 to 35 parts by weight, particularly preferably 3 to 30 parts by weight, further preferably 7 to 25 parts by weight, based on a total of 100 parts by weight of the polyvinyl alcohol-based resin used. When the content of the plasticizer (C) is too small, the tensile properties in the preparation of the polarizing film tend to decrease, and when the content is too large, the stability of the obtained optical polyvinyl alcohol-based film over time tends to decrease. the

In addition, the surfactant (D) used in the present invention has functions of affecting the smoothness of the surface of the film and suppressing the adhesion of the films to each other when rolled up in the form of a roll. For example, anionic surfactants and nonionic surfactants may be used alone or in combination of two or more of them, but, specifically, anionic surfactants and nonionic surfactants are preferably used in combination in view of the transparency of the film. active agent. the

As anionic surfactants, mention may be made, for example:

(1) Aliphatic alkyl sulfonates,

(2) Alkyl sulfate ester salt,

(3) Polyoxyethylene alkyl ether sulfate,

(4) Polyoxyethylene alkylphenyl ether sulfate,

(5) Higher fatty acid alkanolamide sulfate, etc. the

(1) As specific examples of aliphatic alkylsulfonate, there may be mentioned, for example, sodium hexylsulfonate, sodium heptylsulfonate, sodium octylsulfonate, sodium nonylsulfonate, sodium decylsulfonate, sodium dodecylsulfonate, Sodium alkylsulfonate, sodium tetradecylsulfonate, sodium cetylsulfonate, sodium octadecylsulfonate, a mixture of sodium aliphatic alkylsulfonates having 6 to 18 carbon atoms, and the like. Suitably, sodium dodecylsulfonate, sodium tetradecylsulfonate, sodium cetylsulfonate, a mixture of sodium secondary alkylsulfonates having 10 to 18 carbon atoms, and the like are used. In addition, the countercation of the aliphatic alkylsulfonate is not particularly limited, and Na ⁺ , Ca ²⁺ , NH ₄ ⁺ or a mixture thereof may be mentioned. Among them, Na ⁺ is particularly preferable.

(2) As specific examples of alkyl sulfate ester salts, alkali metal salts such as sodium hexyl sulfate, sodium heptyl sulfate, sodium octyl sulfate, sodium nonyl sulfate, sodium decyl sulfate, sodium lauryl sulfate can be mentioned, for example Sodium, sodium tetradecyl sulfate, sodium cetyl sulfate, sodium stearyl sulfate, sodium eicosyl sulfate or their potassium salts; alkaline earth metal salts such as calcium salts; and organic amine salts such as ammonium salts. Suitably, sodium lauryl sulfate, sodium stearyl sulfate, etc. are used. Furthermore, the counter cation is not particularly limited, and Na ⁺ , Ca ²⁺ , NH ₄ ⁺ or a mixture thereof may be mentioned. Among them, Na ⁺ is particularly preferable.

(3) As specific examples of polyoxyethylene alkyl ether sulfates, alkali metal salts such as sodium polyoxyethylene hexyl ether sulfate, sodium polyoxyethylene heptyl ether sulfate, sodium polyoxyethylene octyl ether sulfate, Sodium Polyoxyethylene Nonyl Ether Sulfate, Sodium Polyoxyethylene Decyl Ether Sulfate, Sodium Polyoxyethylene Lauryl Ether Sulfate, Sodium Polyoxyethylene Myristyl Ether Sulfate, Sodium Polyoxyethylene Cetyl Ether Sulfate , sodium polyoxyethylene stearyl ether sulfate, sodium polyoxyethylene eicosyl ether sulfate or their potassium salts; and organic amine salts such as ammonium salts. Suitably, sodium polyoxyethylene lauryl ether sulfate or the like is used. Furthermore, the counter cation is not particularly limited, and Na ⁺ , Ca ²⁺ , NH ₄ ⁺ or a mixture thereof may be mentioned. Among them, Na ⁺ is particularly preferable.

(4) As specific examples of polyoxyethylene alkylphenyl ether sulfate, alkali metal salts such as polyoxyethylene hexylphenyl ether sodium sulfate, polyoxyethylene heptylphenyl ether sodium sulfate, polyoxyethylene Sodium octylphenyl ether sulfate, sodium polyoxyethylene nonylphenyl ether sulfate, sodium polyoxyethylene decylphenyl ether sulfate, sodium polyoxyethylene dodecylphenyl ether sulfate, polyoxyethylene tetradecyl ether Sodium phenyl ether sulfate, sodium polyoxyethylene cetyl phenyl ether sulfate, sodium polyoxyethylene octadecyl phenyl ether sulfate, sodium polyoxyethylene eicosyl phenyl ether sulfate or their potassium salts; and organic amine salts such as ammonium salts. Suitably, sodium polyoxyethylene nonylphenyl ether sulfate or the like is used. Furthermore, the counter cation is not particularly limited, and Na ⁺ , Ca ²⁺ , NH ₄ ⁺ or a mixture thereof may be mentioned. Among them, Na ⁺ is particularly preferable.

(5) As specific examples of higher fatty acid alkanolamide sulfates, ethanolamide sodium caproate sulfate, ethanolamide sodium caprylate sulfate, ethanolamide sodium caprate sulfate, ethanolamide sodium laurate sulfate, ethanol palmitate can be mentioned, for example Amide sodium sulfate, stearic ethanolamide sodium sulfate, oleic ethanolamide sodium sulfate, or potassium salts thereof; and propanolamide compounds and butanolamide compounds substituted for these ethanolamide compounds. Furthermore, the counter cation is not particularly limited, and Na ⁺ , Ca ²⁺ , NH ₄ ⁺ or a mixture thereof may be mentioned. Among them, Na ⁺ is particularly preferable.

Furthermore, in addition to the anionic surfactants of (1) to (5) above, anionic surfactants including sulfate ester salts such as sulfonated oil, higher alcohol ethoxy sulfate salts, and monoglycerin may be used in combination Monoglysulfate; carboxylates such as fatty acid soaps, N-acyl amino acids and their salts, polyoxyethylene alkyl ester carboxylates and acylated peptides; sulfonate types such as alkylbenzenesulfonates, alkyl Naphthalene sulfonate, polycondensate of naphthalene sulfonate and formaldehyde, polycondensate of melamine sulfonate and formaldehyde, dialkyl succinate sulfonate, dialkyl succinate sulfonate, polyoxyethylene succinic acid Alkyl ester sulfonate disalt, alkyl acetate sulfonate, alpha-olefin sulfonate, N-acylmethyl taurate and dimethyl isophthalate-5-sulfonic acid sodium salt; phosphoric acid Types of ester salts such as polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl phenyl ether phosphate and alkyl phosphate, etc. the

On the other hand, as nonionic surfactants, mention may be made, for example:

(7) Polyoxyethylene alkyl ether represented by the following general formula:

RO(C ₂ H ₄ O) _n H

Wherein R represents alkyl or alkenyl, and its number of carbon atoms is 6～22, preferably 8～18; They can be single alkyl or mixed alkyl; And can use from coconut oil, palm oil, palm Alkyl groups with alkyl distribution obtained from kernel oil, tallow, etc.;

(8) Polyoxyethylene alkylphenyl ether represented by the following general formula:

RXO(C ₂ H ₄ O) _n H

Wherein R represents an alkyl group or an alkenyl group, and its number of carbon atoms is 6-22, preferably 8-18; they can be a single alkyl group or a mixed alkyl group; The alkyl group of the alkyl distribution obtained from oil, tallow, etc.; and X represents a phenylene group, and n represents an integer of 1 to 20, preferably 2 to 10;

(9) Higher fatty acid monoalkanolamides or dialkanolamides represented by the following general formula:

RCONH-R′-OH or RCON-(R′-OH) ₂

Wherein R represents an alkyl group or an alkenyl group, and its number of carbon atoms is 6-22, preferably 8-18; they can be a single alkyl group or a mixed alkyl group; An alkyl group of an alkyl distribution obtained from oil, tallow, etc.; and R' represents any one of -C ₂ H ₄ -, -C ₃ H ₆ - and -C ₄ H ₈ -;

(10) Higher fatty acid amides represented by the following general formula:

RCONH ₂

Wherein R represents an alkyl group or an alkenyl group, and its number of carbon atoms is 6-22, preferably 8-18; they can be a single alkyl group or a mixed alkyl group; Alkyl groups with alkyl distribution obtained from kernel oil, tallow, etc.;

(11) Polyoxyethylene alkylamine represented by the following general formula:

RNH(C ₂ H ₄ O) _x H or H(C ₂ H ₄ O) _y N(R)(C ₂ H ₄ O) _x H

Wherein R represents an alkyl group, and its number of carbon atoms is 6-22, preferably 8-18; they can be a single alkyl group or a mixed alkyl group; and x and y each represent an integer of 1-30, preferably 3-15. the

(12) Polyoxyethylene higher fatty acid amides;

(13) amine oxide;

etc. the

(7) As specific examples of polyoxyethylene alkyl ethers, there can be mentioned, for example, polyoxyethylene hexyl ether, polyoxyethylene heptyl ether, polyoxyethylene octyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl Ether, polyoxyethylene lauryl ether, polyoxyethylene myristyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene di Decyl ether etc. Specifically, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and the like are suitable. the

(8) As specific examples of polyoxyethylene alkylphenyl ether, polyoxyethylene hexylphenyl ether, polyoxyethylene heptylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene nonylphenyl ether, phenyl phenyl ether, polyoxyethylene decyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene tetradecyl phenyl ether, polyoxyethylene hexadecyl phenyl ether, polyoxyethylene Octadecyl phenyl ether, polyoxyethylene eicosyl phenyl ether, etc. Specifically, polyoxyethylene nonylphenyl ether is suitable. the

(9) As specific examples of higher fatty acid monoalkanolamides or dialkanolamides, there may be mentioned, for example, caproic acid monoethanolamide or caproic diethanolamide, caprylic acid monoethanolamide or caprylic diethanolamide, capric acid monoethanolamide, Ethanolamide or capric acid diethanolamide, Lauric acid monoethanolamide or lauric acid diethanolamide, Palmitic acid monoethanolamide or palmitic acid diethanolamide, Stearic acid monoethanolamide or stearic diethanolamide, Oleic acid monoethanolamide Ethanolamide or oleic acid diethanolamide, coconut fatty acid monoethanolamide or coconut fatty acid diethanolamide, or propanolamides and butanolamides substituted for these ethanolamides. Among them, alkyl dialkanolamides are preferable, and specifically, lauric acid diethanolamide or coconut oil fatty acid diethanolamide is suitably used. Specifically, diethanolamide and a mixture of diethanolamide and an adduct of diethanolamide [NH—(C ₂ H ₄ OH) ₂ ] produced as a by-product during the production process (molar ratio 1 :2 type) is advantageous.

(10) As specific examples of higher fatty acid amides, caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide and the like can be mentioned, for example. Among them, palmitic acid amide and stearic acid amide are suitable. the

(11) As specific examples of polyoxyethylene alkylamines, there may be mentioned, for example, polyoxyethylene hexylamine, polyoxyethylene heptylamine, polyoxyethylene octylamine, polyoxyethylene nonylamine, polyoxyethylene decylamine Amines, polyoxyethylene dodecylamine, polyoxyethylene tetradecylamine, polyoxyethylene hexadecylamine, polyoxyethylene octadecylamine, polyoxyethylene eicosylamine, etc. Among them, polyoxyethylene dodecylamine is suitable. the

(12) As specific examples of polyoxyethylene higher fatty acid amides, there may be mentioned, for example, polyoxyethylene caproic acid amide, polyoxyethylene caprylic acid amide, polyoxyethylene capric acid amide, polyoxyethylene lauric acid amide, polyoxyethylene myristic acid amide acid amide, polyoxyethylene palmitic acid amide, polyoxyethylene stearic acid amide, polyoxyethylene oleic acid amide, etc. Among them, polyoxyethylene lauric acid amide and polyoxyethylene stearic acid amide are suitable. the

(13) As specific examples of amine oxides, there may be mentioned, for example, dimethyl lauryl amine oxide, dimethylstearyl oxide, dihydroxyethyl lauryl amine oxide and the like. Among them, dimethyl lauryl amine oxide is suitable. the

In addition, in addition to the above-mentioned nonionic surfactants (7) to (13), ethylene oxide derivatives of alkylphenol-formalin condensation polymers; polyoxyethylene-polyoxypropylene block polymerization can be used in combination substances; ether ester nonionic surfactants such as polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil and polyoxyethylene hard castor oil, polyoxyethylene sorbitan fatty acid ester and polyoxyethylene sorbitol sugar alcohol fatty acid esters; and ester-type surfactants such as polyethylene glycol fatty acid esters, sorbitan fatty acid esters, glycerol mono fatty acid esters, propylene glycol fatty acid esters and sucrose fatty acid esters. the

Based on 100 parts by weight of the total polyvinyl alcohol-based resin used, the content of the surfactant (D) is preferably 0.01-1 part by weight, particularly preferably 0.02-0.5 part by weight, further preferably 0.03-0.2 part by weight. When the content of the surfactant (D) is too small, it is difficult to obtain an anti-blocking effect, while when the content is too large, the transparency of the film tends to decrease. the

Furthermore, in the case where an anionic surfactant and a nonionic surfactant are used in combination, the amount of the anionic surfactant is preferably 0.01 to 1 part by weight based on 100 parts by weight of the total polyvinyl alcohol-based resin used, especially It is preferably 0.02 to 0.2 parts by weight, more preferably 0.02 to 0.1 parts by weight, and the amount of nonionic surfactant is preferably 0.01 to 1 parts by weight, particularly preferably 0.02 to 0.2 parts by weight, more preferably 0.03 to 0.1 parts by weight . When the amount of the anionic surfactant is too small, there is a tendency that the dispersibility of the dye decreases and the staining spots increase when the polarizing film is prepared, and when the amount is too large, there is a tendency that the polyvinyl alcohol group is dissolved. The resin foams violently, and air bubbles are easily mixed into the film, whereby the film cannot be used as an optical film. When the amount of the nonionic surfactant is too small, it is difficult to obtain an anti-blocking effect, while when the amount is too large, the transparency and surface smoothness of the film tend to decrease. the

In the present invention, it is also useful to mix an antioxidant in order to prevent yellowing of the film. Examples include any antioxidant such as phenolic antioxidants, and 2,6-di-tert-butyl-p-cresol, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4, 4'-butylenebis(3-methyl-6-tert-butylphenol) and the like are suitable. Antioxidants are used in the range of about 2 to 100 ppm based on the polyvinyl alcohol-based resin. the

Therefore, in the present invention, a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on the side chain or a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on the side chain is used. ) and a polyvinyl alcohol-based resin (B) other than the polyvinyl alcohol-based resin (A), preferably further using a plasticizer (C) and/or a surfactant to form a polyvinyl alcohol-based film. the

Hereinafter, a method for preparing the polyvinyl alcohol-based film of the present invention will be specifically described. In this regard, when the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) are collectively represented, they are sometimes referred to as "polyvinyl alcohol-based resin". the

In the present invention, a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on the side chain or a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on the side chain and A polyvinyl alcohol-based resin (B) other than the polyvinyl alcohol-based resin (A), preferably further using a plasticizer (C) and/or a surfactant, to prepare an aqueous solution of a polyvinyl alcohol-based resin composition, and A polyvinyl alcohol film is prepared by casting the aqueous solution on a drum roll or an endless belt and drying the film to form a film. the

In the production method of the present invention, the polyvinyl alcohol-based resin powder is first washed in order to remove sodium acetate generally incorporated into the resin. In washing, the powder is washed with methanol or water, but the method of washing with water is more preferable because the method of washing with methanol requires solvent recovery and the like. the

Then, the wet cake of the washed water-containing polyvinyl alcohol-based resin was dissolved to prepare an aqueous solution of polyvinyl alcohol-based resin. Since the wet cake of the aqueous polyvinyl alcohol-based resin is not obtained when the desired high-concentration aqueous solution is directly dissolved in water, it is preferably dewatered. The method of removing water is not particularly limited, but a method utilizing centrifugal force is generally used. the

Through the above-mentioned washing and water removal, it is preferable to obtain a wet cake of a water-containing polyvinyl alcohol-based resin having a water content of 50% by weight or less, preferably 30 to 45% by weight. When the water content is too large, it tends to be difficult to adjust the aqueous solution to a desired concentration. the

Then, by adding water, wet cake of the above-mentioned water-containing polyvinyl alcohol-based resin, plasticizer (C), surfactant (D), etc. into the dissolution tank and heating and stirring all to achieve dissolution, the preparation for polyethylene Aqueous solution of film-forming polyvinyl alcohol-based resin composition for alcohol-based film. In the production method of the present invention, specifically, in consideration of solubility, it is preferable to dissolve the wet cake of polyvinyl alcohol-based resin containing water in a dissolution tank equipped with stirring blades of a vertical circulation flow type by introducing steam into the dissolution tank. the

When a wet cake of a polyvinyl alcohol-based resin containing water is dissolved in a dissolving tank equipped with stirring blades of a vertical circulation flow type by introducing steam into the dissolving tank, it is preferable to dissolve the wet cake by introducing steam thereinto in consideration of the ability to dissolve uniformly. Stirring is started when the temperature of the resin reaches 40-80°C, preferably 45-70°C. When the resin temperature is too low, the load on the motor becomes large, and when the temperature is too high, uniform dissolution tends not to be achieved because of the formation of lumps of polyvinyl alcohol-based resin. In addition, it is also preferable to pressurize the inside of the container when the temperature of the resin reaches 90 to 100° C., preferably 95 to 100° C., by introducing steam therein, in consideration of uniform dissolution ability. When the resin temperature is too low, insoluble substances tend to be formed. When the temperature of the resin reaches 130-150° C., the introduction of steam is stopped, and stirring is continued for 0.5-3 hours to achieve dissolution. After dissolution, concentration adjustment is performed to obtain the desired concentration. the

The concentration of the aqueous solution of the polyvinyl alcohol-based resin composition thus obtained is preferably 10 to 50% by weight, more preferably 15 to 40% by weight, particularly preferably 20 to 30% by weight. When the concentration of the aqueous solution is too low, there is a tendency that the drying load becomes large and the productivity is poor, while when the concentration is too large, the viscosity becomes too high and it becomes difficult to achieve uniform dissolution. the

Then, the obtained aqueous solution of the polyvinyl alcohol-based resin composition was subjected to defoaming treatment. As the defoaming method, standing defoaming, defoaming by means of a multi-screw extruder, and the like may be mentioned. In the production method of the present invention, a method of defoaming by means of a multi-screw extruder is preferable in view of productivity. the

After performing the defoaming treatment, the aqueous solution of the polyvinyl alcohol-based resin composition discharged from the multi-screw extruder was introduced into a T-shaped slot die in a specific amount. In addition, the aqueous solution is cast on a drum roll or an endless belt to form and dry a film. the

As the T-shaped slot die, a long and thin rectangular T-shaped slot die is generally used. The temperature of the resin at the outlet of the T-shaped slot die is preferably 80-100°C, more preferably 85-98°C. When the temperature of the resin at the outlet of the T-shaped slot die is too low, fluidity is insufficient. When the temperature is too high, bubbles tend to be formed. the

In casting, a drum roll or an endless belt is used, but it is preferable to use a drum roll in consideration of widening and elongation, uniformity of film thickness, and the like. the

In casting and film formation on a drum roll, for example, the rotation speed of the drum roll is preferably 5 to 30 m/min, particularly preferably 6 to 20 m/min. The surface temperature of the drum roll is preferably 70 to 99°C, more preferably 75 to 97°C. When the surface temperature of the drum roll is too low, drying is insufficient. When the temperature is too high, bubbles tend to be formed. the

Alternatively, the formed polyvinyl alcohol film on the drum roll is dried by passing its front and rear sides through a plurality of drying rolls. The surface temperature of the drying roll is not particularly limited, but is preferably 60 to 100°C, more preferably 65 to 90°C. When the surface temperature is too low, drying is insufficient, and when the temperature is too high, excessive drying occurs and a defective appearance may result. Furthermore, in the present invention, heat treatment is preferably performed after drying. the

As for the heat treatment, there can be mentioned (1) a method of passing the film through rollers (1 to 30 rollers) having a diameter of 0.2 to 2 m, the surface of which has been subjected to hard chrome plating or mirror finishing, and the The roll is adjusted to a temperature of 60 to 180° C., (2) a method using a floating dryer (length: 2 to 30 m, temperature: 80 to 180° C.), and the like. the

The polyvinyl alcohol-based film of the present invention thus obtained has a light transmittance of 90% or more in the entire visible light wavelength range, and is very useful as a polyvinyl alcohol-based film for optics. Therefore, the polyvinyl alcohol-based resin for optics of the present invention is preferably used as a raw material film of a polarizing film. the

Hereinafter, a method of producing the polarizing film of the present invention using the polyvinyl alcohol film for optics of the present invention will be described. the

The polarizing film of the present invention is prepared through the usual steps of dyeing, stretching, crosslinking with boric acid and heat treatment. As a method for producing a polarizing film, there is a method of stretching a polyvinyl alcohol-based film, dyeing it by immersing it in a solution of iodine or a dichroic dye, and then treating it with a boron compound, simultaneously stretching and dyeing it, and then treating it with a boron compound. A method of treating with a boron compound, a method of dyeing with iodine or a dichroic dye, stretching and then treating with a boron compound, a method of dyeing and then stretching in a solution of a boron compound, etc., can be appropriately selected and used . Accordingly, the polyvinyl alcohol-based film (unstretched film) can be stretched, dyed, and further treated with a boron compound alone or simultaneously. However, in consideration of productivity, it is desirable to perform uniaxial stretching during at least one of the dyeing step and the step of treating with a boron compound. the

It is desirable to stretch in the uniaxial direction at a ratio of preferably 3 to 10 times, more preferably 3.5 to 7 times. In this case, slight stretching may also be performed in a direction perpendicular to the stretching direction (to the extent of preventing shrinkage in the width direction or to a greater extent). The temperature during stretching is desirably selected from 20 to 170°C. In addition, the stretching magnification can be finally set within the above-mentioned range, and the stretching operation can be performed not only at one stage in the production step but also within any stage range in the production step. the

Staining of the membrane is generally performed by contacting the membrane with a liquid containing iodine and a dichroic dye. Usually, iodine-potassium iodide aqueous solution is used, and preferably the concentration of iodine is 0.1-2 g/L, the concentration of potassium iodide is 10-50 g/L, and the weight ratio of potassium iodide/iodine is 20-100. The dyeing time is practically about 30 to 500 seconds. The temperature of the treatment bath is preferably 5 to 50°C. In addition to the aqueous solvent, a small amount of water-miscible organic solvent can be introduced. As a method for contacting, any method such as dipping, coating and spraying can be employed. the

The dyed membrane is then treated with a boron compound. As the boron compound, boric acid or borax is practical. The boron compound is preferably used in the form of an aqueous solution or a water-organic solvent mixed solution at a concentration of 0.3 to 2 mol/L. In solution, the coexistence of a small amount of potassium iodide is actually desirable. As a treatment method, a dipping method is desirable, but a coating or spraying method is also possible. The temperature at the time of treatment is preferably about 20-60° C., and the treatment time is preferably 3-20 minutes. In addition, stretching operations can be performed during processing, if desired. the

After laminating and adhering an optically anisotropic polymer film or sheet as a protective film on one surface or both surfaces of the polarizing film of the present invention thus obtained, the polarizing film of the present invention thus obtained can be used as a polarizer piece. As the protective film used for polarized light polarization according to the invention, mention may be made, for example, of cellulose triacetate, cellulose diacetate, polycarbonate, polymethylmethacrylate, polystyrene, polyethersulfone, polyarylate, poly4 - Methylpentene, polyphenylene ether, cyclo-based polyolefin or norbornene-based polyolefin, etc. the

In addition, for the purpose of thinning the film, instead of adhering the above protective film on the polarizing film, a curable resin such as urethane-based resin, acrylic resin or urea resin may be coated on one surface of the polarizing film or Laminate on both surfaces. the

If necessary, after forming a transparent pressure-sensitive adhesive layer on one surface thereof by a generally known method, sometimes the polarizing film (including a film having a protective film or a curable resin laminated on at least one surface) ) into practical application. As the pressure-sensitive adhesive layer, it is particularly preferable to mainly comprise an acrylate such as butyl acrylate, ethyl acrylate, methyl acrylate or 2-ethylhexyl acrylate with an α-monoolefin carboxylic acid such as acrylic acid, maleic acid, Adhesive layers of copolymers of itaconic acid, methacrylic acid, or crotonic acid (including copolymers to which vinyl monomers such as acrylonitrile, vinyl acetate, or styrene are added) because they do not inhibit the polarizing properties of polarizing films . However, any pressure-sensitive adhesive having transparency may be used without being limited thereto, and a polyvinyl ether-based pressure-sensitive adhesive or a rubber-based pressure-sensitive adhesive may be used. the

The polarizing film of the present invention is preferably used in desktop electronic calculators, electronic clocks or watches, word processors, personal computers, televisions, portable information terminals, liquid crystal display devices such as equipment for automobiles and machines, sunglasses, goggles, 3D Glasses, reflection reducing layers for display devices (CRT, LCD, etc.), medical equipment, construction materials, toys, etc. the

Example

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. the

In the examples, "parts" and "%" refer to "parts by weight" and "% by weight", respectively, unless otherwise specified. the

Each physical property is measured as follows:

(1) The amount of 1,2-diol bonds on the side chain

Measured by ¹ H-NMR measurement and calculation (internal standard substance: tetramethylsilane, solvent: d6-DMSO).

(2) Saponification degree of polyvinyl alcohol-based resin

Analyzed by the alkali consumption required to hydrolyze the remaining vinyl acetate units. the

(3) Viscosity of 4% aqueous solution of polyvinyl alcohol-based resin

粘度计( 

viscometer)进行测量。  By adjusting the water temperature to 20°C in

Viscometer (

viscometer) to measure.

(4) Optical properties

Using a Multi Channel Retardation Measuring System (RETS-2000 manufactured by Otsuka Electronics Co., Ltd.), the degree of polarization, light transmittance and dichroic ratio. the

Example 1

Put into 42kg polyvinyl alcohol base resin (A), 100kg water, 4.2kg as plasticizer (C) glycerol, 21g as surfactant (D) sodium dodecylsulfonate and 8g of polyoxyethylene-dodecylamine, the polyvinyl alcohol-based resin (A) has a 4% aqueous solution with a viscosity of 107 mPa·s, a degree of saponification of 99.3 mol%, and 1,2- The amount of diol bonds was 1 mol%, and the whole was heated to 150° C. with stirring, and uniformly dissolved. Thereafter, an aqueous solution of a polyvinyl alcohol-based resin composition having a concentration of 26% was obtained after concentration adjustment. the

Then, an aqueous solution (liquid temperature: 147° C.) of a polyvinyl alcohol-based resin composition was fed into a twin-screw extruder, and defoaming was performed. The defoamed aqueous solution of the polyvinyl alcohol-based resin composition was cast from a T-shaped slit die onto a casting roll to form a film. Casting/film forming conditions are as follows:

drum roller:

Diameter (R1): 3200mm, width: 4.3m, rotation rate: 8m/min, surface temperature: 90°C, resin temperature at the exit of the T-shaped slot die: 95°C. the

The front side and the back side of the obtained film were alternately passed through drying rolls under the following conditions to achieve drying. the

Drying Roller:

Diameter (R2): 320 mm, width: 4.3 m, number of rolls: 10 rolls, rotation rate: 8 m/min, surface temperature: 80°C. the

The film was heat-treated at 140° C. by means of a floating type drier (length: 18.5 m) from which hot air was floated Blow continuously to both sides of the film in a type dryer. the

Using the polyvinyl alcohol base film for optics of the present invention obtained above, a polarizing film was obtained as follows, and then the polarizing performance was evaluated. the

The obtained polyvinyl alcohol base film for optics was immersed in a water bath at a water temperature of 30° C., and stretched at a magnification of 1.5 times. Then, the film was immersed in a dyeing tank (30° C.) containing 0.2 g/L iodine and 15 g/L potassium iodide for 240 seconds, and stretched at a magnification of 1.3 times. Further, the film was dipped into a boric acid treatment tank (40° C.) containing a composition of 50 g/L boric acid and 30 g/L potassium iodide, and simultaneously performed uniaxial stretching and boric acid treatment at a magnification of 2.8 times over 5 minutes. Thereafter, the film was dried to obtain a polarizing film. the

Then, using a polyvinyl alcohol-based aqueous solution as an adhesive, a triacetyl cellulose film having a film thickness of 80 μm was adhered to both surfaces of the obtained polarizing film, and the whole was dried at 50° C. to obtain a polarized piece. Regarding the polarizing plate, the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, a film with very high polarizing properties at a wavelength of 460 nm was obtained. the

Separately, stretching was performed under the following conditions, and a critical stretch ratio was determined. the

(Evaluation of critical stretch ratio)

The polyvinyl alcohol-based film was immersed in a water bath at a water temperature of 30° C., and stretched at a magnification of 1.5 times. Then, the film was immersed in a dyeing tank (30° C.) containing 0.2 g/L iodine and 15 g/L potassium iodide for 240 seconds, and stretched at a magnification of 1.3 times. In addition, the membrane was immersed in a boric acid treatment tank (40° C.) containing a composition of 50 g/L boric acid and 30 g/L potassium iodide, and monolithography was performed on the membrane at an amplification rate of 40% per minute before immersion in the boric acid treatment tank. Shaft stretched. The total stretch ratio at break with respect to the raw material film was regarded as a critical stretch ratio, and evaluated according to the following evaluation criteria. the

A: 6.3 times the critical stretch ratio;

B: 6.0 times to less than 6.3 times the critical stretch ratio;

C: Critical stretch ratio of 5.7 times to less than 6.0 times;

D: A critical draw ratio of less than 5.7 times. the

Example 2

In the same manner as in Example 1, a polyvinyl alcohol-based film for optics (length: 4000 m, width 4 m, thickness 50 μm) was obtained, except that, as the polyvinyl alcohol-based resin, the resin (A) was changed to 21 kg polyethylene Alcohol base resin (A) and 21kg unmodified polyvinyl alcohol base resin (B), the viscosity of the 4% aqueous solution that described polyvinyl alcohol base resin (A) has is 107mPa·s, saponification degree is 99.3 mol%, and the amount of 1,2-diol bonds on the side chains is 1 mol%, the viscosity of a 4% aqueous solution of the unmodified polyvinyl alcohol-based resin (B) is 64 mPa·s, and the degree of saponification is 99.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, a film with very high polarizing properties at a wavelength of 460 nm was obtained. In addition, the evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Example 3

In the same manner as in Example 1, a polyvinyl alcohol base film for optics (length: 4000 m, width 4 m, thickness 65 μm) was obtained, except that, as the polyvinyl alcohol base resin, resin (A) was changed to 6.3 kg polyvinyl alcohol base film. Vinyl alcohol-based resin (A) and 35.7 kg of unmodified polyvinyl alcohol-based resin (B), said polyvinyl alcohol-based resin (A) has a 4% aqueous solution with a viscosity of 16 mPa·s and a degree of saponification of 99.7 moles %, and the amount of 1,2-diol bonds on the side chains is 6 mol%, the viscosity of a 4% aqueous solution of the unmodified polyvinyl alcohol-based resin (B) is 64mPa·s, and saponification The degree is 99.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, a film with very high polarizing properties at a wavelength of 460 nm was obtained. In addition, evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Example 4

In the same manner as in Example 1, a polyvinyl alcohol base film for optics (length: 4000 m, width 4 m, thickness 65 μm) was obtained, except that, as the polyvinyl alcohol base resin, resin (A) was changed to 12.6 kg polyvinyl alcohol base film. Vinyl alcohol-based resin (A) and 29.4 kg of unmodified polyvinyl alcohol-based resin (B), said polyvinyl alcohol-based resin (A) has a 4% aqueous solution with a viscosity of 30 mPa·s and a degree of saponification of 99.2 moles %, and the amount of 1,2-diol bonds on the side chains is 1 mole%, the viscosity of a 4% aqueous solution of the unmodified polyvinyl alcohol-based resin (B) is 64mPa·s, and saponification The degree is 99.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, a film with very high polarizing properties at a wavelength of 460 nm was obtained. In addition, the evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Example 5

In the same manner as in Example 1, a polyvinyl alcohol base film for optics (length: 4000 m, width 4 m, thickness 65 μm) was obtained, except that, as the polyvinyl alcohol base resin, resin (A) was changed to 25.2 kg polyvinyl alcohol base film. Vinyl alcohol-based resin (A) and 16.8 kg of unmodified polyvinyl alcohol-based resin (B), said polyvinyl alcohol-based resin (A) has a 4% aqueous solution with a viscosity of 107 mPa·s and a degree of saponification of 99.3 moles %, and the amount of 1,2-diol bond on the side chain is 1 mole%, the viscosity of the 4% aqueous solution of the unmodified polyvinyl alcohol-based resin (B) is 64mPa·s, and the saponification The degree is 99.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, a film with very high polarizing properties at a wavelength of 460 nm was obtained. In addition, evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Example 6

In the same manner as in Example 1, a polyvinyl alcohol base film for optics (length: 4000 m, width 4 m, thickness 65 μm) was obtained, except that, as the polyvinyl alcohol base resin, the resin (A) was changed to 2.1 kg polyvinyl alcohol base film. Vinyl alcohol-based resin (A) and 39.9 kg of unmodified polyvinyl alcohol-based resin (B), said polyvinyl alcohol-based resin (A) has a 4% aqueous solution with a viscosity of 16 mPa·s and a degree of saponification of 99.8 moles %, and the amount of 1,2-diol bonds on the side chains is 8 mol%, the viscosity of a 4% aqueous solution of the unmodified polyvinyl alcohol-based resin (B) is 64mPa·s, and saponification The degree is 99.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, a film with very high polarizing properties at a wavelength of 460 nm was obtained. In addition, the evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Comparative example 1

In the same manner as in Example 1, a polyvinyl alcohol-based film (length: 4000 m, width 4 m, thickness 50 μm) was obtained, except that, as the polyvinyl alcohol-based resin, resin (A) became 42 kg of unmodified A polyvinyl alcohol-based resin, the unmodified polyvinyl alcohol-based resin had a 4% aqueous solution viscosity of 64 mPa·s, and a degree of saponification of 99.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, the dichroic ratio at a wavelength of 460 nm was 31.72, and sufficient polarization performance was not obtained. In addition, the evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Comparative example 2

In the same manner as in Example 1, a polyvinyl alcohol-based film (length: 4000 m, width 4 m, thickness 50 μm) was obtained, except that the polyvinyl alcohol-based resin (A) was changed to polyvinyl alcohol-based resin (A) , the polyvinyl alcohol-based resin (A) had a 4% aqueous solution viscosity of 110 mPa·s, a degree of saponification of 99.8 mol%, and an amount of 1,2-diol bonds on side chains of 8 mol%. the

With the obtained polyvinyl alcohol-based film, an attempt was made to form a polarizing film, but water resistance was insufficient, and a polarizing film could not be obtained. the

Comparative example 3

In the same manner as in Example 1, a polyvinyl alcohol-based film (length: 4000m, width 4m, thickness 50μm) was obtained, except that, as the polyvinyl alcohol-based resin, resin (A) was changed to 42kg polyvinyl alcohol-based Resin, the polyvinyl alcohol-based resin had a 4% aqueous solution viscosity of 27 mPa·s, a degree of saponification of 99.8 mol%, and an amount of 1,2-diol bonds on side chains of 1.8 mol%. the

With the obtained polyvinyl alcohol-based film, a polarizing film and a polarizing plate were obtained in the same manner as in Example 1, and the degree of polarization and light transmittance were measured. Table 1 shows the measurement results. As shown in Table 1, the dichroic ratio at a wavelength of 460 nm was 27.01, and sufficient polarization performance was not obtained. In addition, the evaluation of the critical draw ratio was performed individually in the same manner as in Example 1. Table 1 shows the measurement results. the

Table 1

Although the present invention has been described in detail and in conjunction with its specific embodiments, it is obvious to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the present invention. the

This application is based on Japanese Patent Application 2005-024466 filed on January 31, 2005, Japanese Patent Application 2005-024467 filed on January 31, 2005, Japanese Patent Application 2005-024 filed on November 22, 2005 336441 and Japanese Patent Application No. 2005-336442 filed on November 22, 2005, and the contents thereof are incorporated herein by reference. the

Industrial applicability

The polyvinyl alcohol-based film for optics of the present invention is a polyvinyl alcohol-based resin in which the polyvinyl alcohol-based resin is composed only of a polyvinyl alcohol-based resin (A) containing a 1,2-diol bond on the side chain and a 1,2-diol bond on the side chain - a film in which the amount of diol bond is 0.01 to 6 mol %; or use a specific ratio of polyvinyl alcohol-based resin (A) containing 1,2-diol bond on the side chain and a polyvinyl alcohol-based resin (A) other than polyvinyl alcohol-based resin (A ) other than polyvinyl alcohol-based resin (B), so that it is a polyvinyl alcohol-based film excellent in tensile properties, and has the ability to obtain a polarizing film excellent in polarizing properties in the entire visible light wavelength range, specifically around a wavelength of 460nm Effect. The film is used as a device for desktop electronic calculators, electronic clocks or watches, word processors, personal computers, televisions, portable information terminals, liquid crystal display devices such as for automobiles and machines, sunglasses, goggles, 3D glasses, Raw material films for polarizing films used in anti-reflection layers of display devices (CRT, LCD, etc.), medical equipment, building materials, toys, etc., as raw material films for 1/2 wavelength plates and 1/4 wavelength plates, and as The raw material film used for the retardation film of a liquid crystal display device is very useful. the

Claims (11)

1. A polyvinyl alcohol-based film for optics containing a polyvinyl alcohol-based resin, Wherein the polyvinyl alcohol-based resin comprises a polyvinyl alcohol-based resin (A) having a 1,2-diol bond on the side chain and having a degree of saponification of 98 mol% or more and a polyvinyl alcohol-based resin (A) other than the polyvinyl alcohol-based resin (A) Other polyvinyl alcohol-based resins (B) with a degree of saponification of 98 mol% or more, The difference in degree of saponification between the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) having a 1,2-diol bond on the side chain is 3 mol% or less, Based on the total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), the content of the polyvinyl alcohol-based resin (A) is 5 to 30% by weight, and The polyvinyl alcohol-based resin satisfies the following formula (1): 0.01≤A×G/(A+B)≤6(1) Where A represents the weight ratio of the polyvinyl alcohol-based resin (A) based on the total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), and B represents the polyvinyl alcohol-based resin ( B) Weight ratio, G represents the amount in mole % of 1,2-diol linkages on the side chains. 2. The polyvinyl alcohol-based film for optics according to claim 1, wherein the amount of 1,2-diol bonds on the side chains of the polyvinyl alcohol-based resin (A) is 0.05 to 20 mol%. 3. The polyvinyl alcohol-based film for optics according to claim 1, wherein the polyvinyl alcohol-based resin (A) has a viscosity of 8 to 400 mPa·s as a viscosity of a 4% by weight aqueous solution. 4. The polyvinyl alcohol-based film for optics according to claim 1, wherein the polyvinyl alcohol-based resin (B) has a viscosity of 8 to 500 mPa·s as a viscosity of a 4% by weight aqueous solution. 5. The polyvinyl alcohol-based film for optics according to claim 1, further comprising a plasticizer (C). 6. The polyvinyl alcohol-based film for optics according to claim 1, further comprising a surfactant (D). the 7. The polyvinyl alcohol-based film for optics according to claim 1, wherein the film has a width of 2 m or more. 8. The polyvinyl alcohol-based film for optics according to claim 1, wherein the film has a thickness of 30 to 70 [mu]m. 9. The polyvinyl alcohol-based film for optics according to claim 1, which is used as a raw material film of a polarizing film. 10. A polarizing film comprising the optical polyvinyl alcohol-based film of claim 1. 11. A polarizing plate comprising the polarizing film of claim 10 and a protective film provided on at least one face of the polarizing film. the